1. Field of the Invention
The invention relates to cyclonic separators and more specifically to cyclones for separating fluid containing mixtures.
A cyclone typically comprises a housing defining a chamber having an upper cylindrical section and a lower conical section with its large diameter portion adjacent the cylindrical section. The mixture to be separated is directed against the wall of the cylindrical section of the chamber in a horizontal, tangential direction by means of a tangentially disposed inlet communicating therewith. This results in the mixture flowing along the chamber wall in a downwardly spiraling path. The reduction in diameter downwardly along the chamber wall in the conical section causes angular acceleration of the flowing mixture. The heavier constituents of the mixture move radially outwardly toward the chamber wall under centrifugal force and continue spiraling down the wall, while the lighter constituents flow upwardly through a vortex formed centrally of the chamber. The light constituents are removed from the chamber through an outlet communicating with the upper end of the chamber, the heavy constituents being removed through an outlet communicating with the small diameter portion of the conical section at or near the lower end.
The mixtures which are handled in cyclones, particularly the heavier constituents, which usually are solids, which flow along the chamber walls, are often of an abrasive nature. Thus, their flow along the walls can cause considerable wear especially since they are moving rapidly and are forced against the walls, by centrifugal force. This wear is usually particularly pronounced at the smaller diameter portion of the conical section where the centrifugal force is highest and the heavy constituents, usually solids, are most concentrated.
2. Description of the Prior Art
Because of the wear problem caused by the materials handled in cyclones, it is customary to provide a replaceable liner in the chamber of the housing to protect the inner walls of the housing. Of course, it is most desirable that the liner be as highly wear resistant as possible under the operating conditions in which it will be used. One of the problems encountered in the use of such liners is the expense of replacing them when they become worn. Unfortunately, many of the highly wear resistant materials which would otherwise be preferred for use in liners are so expensive that they become impractical for that use. Many of these materials are also impractical for certain applications because of their physical characteristics. For example, in some cases it is necessary, or at least desirable, that the liner be somewhat flexible to facilitate insertion into the cyclone chamber. In such cases many of the best wear resistant materials for certain operating conditions, such as metals, hard synthetic resins, ceramics, glasses and tungsten carbide, are eliminated because of their rigidity. In other cases, a rigid liner is more appropriate, and relatively flexible materials, such as soft synthetic resins, can not be used. Furthermore, most liners are subjected to various types of shocks caused, for example, by vibrations of the cyclone, thermal shocks, mechanical impacts, etc. Thus, frangible materials such as glasses and ceramics, although they have excellent wear resistance characteristics under many operative conditions, can not ordinarily be used.
Thus, in the past, relatively inexpensive materials having certain physical characteristics have often been chosen for use in liners at the expense of high wear resistance characteristics.
Present attempts to solve this problem involve the use of liners having two separate parts disposed longitudinally adjacent each other. The cyclone housings may or may not also comprise two parts which are flange-fitted together or otherwise connected. The lower part of the liner is formed of a preferred wear resistant material, and the upper part of another material. Such designs are not satisfactory for many reasons. Because of the precision fits required between the two parts of the liner, between the two parts of the housing, and between the parts of the liner and the housing, cyclones and liners of this type are difficult and expensive to manufacture. Even at best, they are seldom properly fitted. Furthermore, where frangible materials are used in the liners, they are easily broken or damaged during installation and/or operation.